The Minnesota Community Prevention Program, now called the Minnesota Heart Health Program (MHHP), is a community-based research demonstration of the effect of multiple educational strategies at the level of whole populations to encourage more healthy behavior, prevent cardiovascular diseases (CVD) and promote health. The rationale is based on the important demonstrated influence of blood pressure, blood lipids, and cigarette smoking on CVD risk and the effect of mass health behaviors on population levels of these factors. The research strategy employed has elements of control (education and comparison communities), repetition (staged introduction at annual intervals), trend measures in population samples and cohorts of individuals, dose-effect measurement according to exposure, linkage analysis between components of the program, and pooling of education and comparison results. Educational strategies include: a) direct "hands-on" education; b) professional education to enhance prevention services; c) organization and training of community leaders; d) mass communications; and e) enhanced community support for healthy behavior. The strong components herein of design, methods development, and evaluation of the educational program are all essential to produce new knowledge in this early period of national concern for prevention and health promotion. This public health trial or demonstration uses optimally a host of existing facilities in Minnesota and a long experience in community studies, risk reduction trials, and extension education. The MHHP plans to leave, on completion of the research and development, well-established mechanisms to maintain a more healthy behavior in Minnesota communities. It is designed to demonstrate new and important issues for the future of preventive efforts in public health.